The present invention relates to a device for regulating an internal combustion engine in a motor vehicle, with an electrical desired-value transmitter that is adjustable between an idling and a full-load position by an accelerator pedal. An actuator actuates a regulating member mechanically coupled to the actuator. An electrical control unit connected between the actuator and the desired-value transmitter receives set position signals from the desired-value transmitter and outputs control signals to control the actuator. A mechanical transmission element of variable length is connected between a connecting lever that is connected to the desired-value transmitter, and the regulating member.
A device of this general type is shown in German Published Unexamined Patent Application No. 3,307,968. In this device, the position of the connecting lever and the part of the mechanical transmission element fixedly connected to the connecting lever is directly dependent on the position of the desired-value transmitter and therefore of the accelerator pedal. Consequently, although an emergency running is ensured in the event of a failure of the electrical transmission means, nevertheless, despite idle travels in the mechanical transmission element, it is possible to enter additional functions only to a limited extent. These idle travels make it impossible for the position of the regulating member to be returned accurately to the region of the desired-value transmitter via the mechanical transmission element, so that signals which are dependent on the position of the regulating member and which are necessary for operating the internal combustion engine or the vehicle cannot be picked up in the region of the desired-value transmitter.
An object of the present invention is to provide a regulating device that, without impairing the emergency running properties and the input of additional functions, provides in the region of the desired-value transmitter a signal dependent on the position of the regulating member and intended for controlling the operation of the internal combustion engine or of the motor vehicle.
This and other objects of the present invention are achieved in the provision of a device according to a preferred embodiment of the present invention for regulating an internal combustion engine with a drag lever that connects the accelerator pedal to a desired-value transmitter. The drag lever drags the connecting lever (connected to the desired-value transmitter) along with the drag lever during the adjustment of the drag lever in the full-load position. The connecting lever is adjustable independently of the drag lever by adjusting means if the drag lever is not at full-load position. The connecting lever is further operatively connected to signal output means for activating the power transmission between the internal combustion engine and the vehicle drive, in response to movement of the connecting lever.
The device according to the invention provides control of the internal combustion engine under emergency running conditions via the mechanical transmission element, without the input and transmission of additional functions to the regulating member being disturbed by the transmission element.
Furthermore, the device according to the invention offers an advantage, under specific operating conditions, such as when under this operating condition, the position of the accelerator pedal differs from the position of the regulating member, this regulating member being critical for controlling vehicle units such as the gear shift of an automatic transmission. The advantage is that the signal for this control at the connecting lever is available at the desired-value transmitter. Thus, when the desired-value transmitter is in an appropriate position, on vehicles in which either the device according to a preferred embodiment of the invention or a purely mechanical linkage for regulating the internal combustion engine is installed, the signal for controlling the vehicle unit is available at the same place and in the same form. Therefore, both the linkage between the accelerator pedal and the desired-value transmitter and the transmission device for the signal can have an identical design in both types of regulation, thus resulting in a considerable simplification in construction.
The connection of the signal output means to a gear change circuit of an automatic transmission provided in a preferred embodiment of the present invention, provides control of special parts in the power transmission of the motor vehicle.
A mechanical transmission element is part of a preferred embodiment of the device according to the present invention, and makes a rigid connection between the regulating member and the connecting lever. Due to this element, the connecting lever is not adjusted further in the direction of full load than the regulating member, yet the transmission element allows this differing adjustment to be made under normal driving conditions, and at the same time makes it possible to transmit the adjustment to the regulating member under emergency running conditions.
In a further preferred embodiment, the regulating shaft is mounted with permanent accuracy because of its direct interaction with the electrical parts of the desired-value transmitter. This is difficult because of the short length of the desired-value transmitter. By so mounting the regulating shaft, it is relieved of all the forces exerted by the regulating devices.
The fastening of the desired-value transmitter to the engine, as provided in certain preferred embodiments of the present invention, offers the advantage that the entire regulating linkage between the accelerator pedal and the internal combustion engine, together with its transmission ratios, plays, resistances and restoring forces, can have the same design, irrespective of whether a purely mechanical regulating linkage or an electrical regulating system, as provided in certain preferred embodiments of the present invention, is installed.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.